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Assessing and correcting fore/aft alignment - Page 3

post #61 of 84

The ramp angle (delta) of many demo bindings is indeed greater than that of regular bindings. I've measured demo set-ups that were as much as three or four mm taller at the heel than the companies regular bindings and told about some that were even greater up to seven mm. And you bet it makes a difference, ever have someone love skis when they dimoed them and then wasn't as impressed with then after purchase. This change in ramp could be the reason.

Of course I get mighty strange looks when I demo skis and measure the binding height and then change the thickness of the heel lift in my boot. But I do it anyway.

post #62 of 84
Bingo milesb, that is why I am not a big proponent of demoing skis.
Yndar, I am suprised by the increase in ramp of the demo bindings that you measured. Most demo bindings are near zero delta due to the fact that the toe piece and the heel piece can move.
post #63 of 84
Pierre eh,

You are right in that most modern rental bindings have much less ramp than they did when they had fixed toes and I didn't have reason to measure a lot of last years crop of bindings so my comment may be based on outdated data and the one pair of demos I did notice last year that had a lot of ramp. Less ramp on demos would make evaluating them more accurate but we are still faced with all the other variables like tune, wax (or lack of it), etc. Like you I'm not a big fan of demoing

post #64 of 84
SCSA, do you have short and/or tight Achilles tendons? If so, that could limit how low you can go in a squat.

Never thought of this, but would tight achilles tendons effect fore/aft alignment?

BTW, sport specific fitness programs are doing a good deal of work on exercises that explore fore/aft alignment. Obviously not as good as working on actual snow, but a start, nonetheless.
post #65 of 84
Dear Lisamarie,

I'll post some new pictures this weekend with me standing in my skis. I will take a picture of me in bare feet, flexing my ankles, as I don't know if I have short ankles or not.
post #66 of 84

Short/tight achilles is one of the factors that can affect fore/aft alignment. Because we have been given the info that SCSA skis with a lot of ankle flex (he can bring himself into fore/aft balance many people with short/tight achilles can't achieve this in ski boots) I would guess that his Achilles is not the problem. One indicator of short/tight achilles is if the subject has to lift their heel to maintain balance in a squat preformed in regular shoes or bare foot.

post #67 of 84

In barefeet, I can do those squats fine. I can get lower the horizontal.

Got to go now, I'll catch up with you all this weekend.

post #68 of 84
Long thighs and relatively short upper body will make it more difficult to go into a deep squat. Lack of flexibility in the ankles will add to the problem.

The best olympic weightlifter (they need to go into deep squates with huge weights) have very short thighs and "normal" upper bodies.

So SCSA, if you have long legs you may have more trouble doing deep squats than me, who has normal thighs (relative to the upper body). I look forward to see the picture too.
post #69 of 84
SCSA if you are going to take a picture of ankle flex then sit in a chair with your thighs horizontal to the floor, your lower leg 90deg vertical and your foot flat on the floor. Now leave your heel on the floor and lift your toes with only your muscles. This is the test that will tell us dynamic motion ability.
post #70 of 84
Pierre, I am surprised at how you do the ankle test! The test you describe tells me more about my shin muscles' ability to flex. I can get far better angles when flexing ankles while standing on a flat surface. "My test" focuses directly on achiles tendon + calf muscle flexibility.

Can you explain the reasoning for your test. I think I need to be educated.
post #71 of 84
TomB what you need to understand is that when sliding you can not effectively flex further than what you can do in dosi-flexion with your muscles. For instance, you can not push on the ground like you have described because there is little friction to do so. We all have great ankle flex standing on a hard surface but the only ankle flex that counts is the amount that you can do with only your shin muscle as you call it. This is also one of the main reasons for being tall.
post #72 of 84

Sorry for the delay in getting back to you, haven't had the time for a longer post this week just a few short ones.

I agree with you that my use of heel lifts doesn't fit with conventional theory or really logical thinking on the subject. When I think about it the fact that I can have someone do the squat test, measure how much I have to raise the heel of the boot for them to get all the way down then put that much lift inside the boot and they are then able to preform the full squat it just doesn't make sense. My mind tells me that the two different ways of raising the heel, one which changes forward lean one which has no effect on forward lean, should produce different results but they don't. Let me throw out another idea that I've toyed with.

All this toying with ramp angle has no direct effect what so ever on the position of the CM. At rest we want to position our CM over a small area between out feet and somewhere about two thirds back along the length of our feet, for ease in writing this I'm going to call this our balance point. If we move the CM to far in front of this balance point then we start to fall forward and must start walking. If I force my ankle to have a set bend in it that differs from its natural resting flex position (which we do with ski boots) then my other joints (knee, hip, spine) have to flex in ways to compensate for this and keep the CM over the balance point. When I raise or lower the heel of a subject I affect this point moving it either toward the toes or toward the heel. When this happens the body must make adjustments to keep the CM over this relocated balance point. I know this must sound way out there to you (it does to me) but it does explain what I observe and that is what I am trying to do.

One of the comments in the letter that HH wrote that was posted by SCSA ties in with this I think. It was about a relationship between the center of hip position and the line defined by the midpoint of the boot sole. I think that this may be the point which defines the farthest forward point which we can move the CM over before we must move the feet forward to keep from falling. Let me talk my way through this and see if it makes any sense.

I have a resting balance point which I position my CM over and I can maintain this position with no muscular effort. I can move my CM forward of this point and stay at rest, because of the structure of my feet, but I must use muscular effort to maintain this position. There is a limit to how far forward I can move the CM before the whole system tips over and no amount of muscular effort will prevent this. Again for ease in thinking about this and writing about it I am going to call this the movement point. There is a small distance between the balance point and the movement point, probably measured in mms. For the sake of argument let's consider the movement point fixed. Raising the heel moves the resting balance point forward (you referred to a heel lift making you feel balanced more forward) closer to the movement point. This means that it requires less movement of the CM to produce forward movement. It is easier to move forward which is one of the prime requirements of skiing.

This would mean that what I am doing when I "align someone in the fore/aft plane" is to bring the resting balance point and the movement balance point closer together so that the subject can move forward with a minimum of deviation from their "natural athletic stance".

Does any of the above make any sense to you?

By the way, I do allow for the ramp angle of the binding when I do the squat test by placing a spacer under the heel to raise it as much as the ramp of the binding does. I have also found that the squat test is a very accurate method of determining how much adjustment in ramp a subject needs. It somehow takes into account all the variables involved in this complicated subject and gives me a measurement I can use as a "fix". And once I make this "fix" I find that further adjustments (based on on-hill feedback) are minimal. It even predicted that I would need a 4cm (yes that's cm) plus adjustment and guess what, it worked. By the way this is the kind of ramp used to allow someone with fused ankles to ski and while my ankle flex may be slightly less than normal they are by no means fused. Something else caused my extreme fore/aft mis-alignment but the ramp, most of it in the boot, has solved the problem.

Your idea about the four scales is very intriguing and if I can find and afford scales that are suitable for setting up such a contraption I may set one up in my shop just to see the data that it can produce.

Anyway I've produced another long post so I'll end here with my usual thanks for keeping my mind from becoming fuzzy, or helping it become fuzzy, I'm not always sure which is happening sometimes.
post #73 of 84
Thats the most laughs I have had in a long time ..short fat calves with slim archilles, long legs and nude squats standing tall with duck feet...hoooootttt :

Sounds like a classic Raichle Flexon comps stance : [img]smile.gif[/img]

<FONT COLOR="#800080" SIZE="1">[ October 14, 2001 04:56 AM: Message edited 2 times, by man from oz ]</font>
post #74 of 84
Thread Starter 

I'm not sure this post is worthwhile for anyone to read except you so I offer my apologies if someone spends the time and finds this excessive and too esoteric.

I really like your post because for me this type of model development and conceptualization (whether it is exactly "correct" or not) is the very same way I work in my academic endeavors and it allows me to think about these issues in a different way. The first time I skimmed your post I was in pretty close agreement. However, the second time around I'm not quite so sure. I'll make a few points for now and perhaps leave some room for a private discussion if you'd like to follow up.

First, I like the idea of a "movement point." In terms of skiing I would probably name this something else, however, since we have a huge cantilever in front of us (the ski) and we don't start moving (walking) automatically if we get beyond that point. I think that we could find a better concept than forward movement that would more closely fit the goal of a balanced position for better and easier control of the skis. Second, to move the balance point forward a person has to make postural changes. I would postulate that this happens, effectively, only if the new position of balance permits a "more comfortable posture." This becomes a balance between increases and decreases of the forces around the joints involved. For example, moving the balance point forward may require further deviation from the most comfortable ankle "resting" angle but reduce the force required by the quads. Another important factor here that enters the balance of this equation is the (hopefully improved) comfort level a person feels in terms of control of their skis. I think this last point is what others (Perhaps Tom B I think) are thinking about when they talk about changing the balance point through proper instruction. I have the notion that effectively moving the CM forward (relative to the ski of course) requires both improved postural and skiing comfort.

Now, in terms of running some experiments. I would love to be involved in a study of fore/aft balance. I wonder if you have the willingness, time, and "subjects" to actually run a somewhat controlled experiment using the setup I described. The options you might have for some on-slope follow up would also be of great advantage. If you do I would love to collaborate with you on this. My goal would be to generate enough meaningful data that we could present at least a preliminary model of fore/aft alignment and perhaps even try to present it at the International Congress on Skiing and Science in Europe next year. This probably sounds a bit far-fetched, but if not send me a private message and we can talk further about the possibility. (BTW, I would be more than happy to fund the "equipment" needed for the study). Also, if there were any other "crazies" here who might be interested in such a study I would be happy to talk to you as well.
post #75 of 84
post #76 of 84
Oh no! I should stay out of this but I can't since it borders on what I do for a living. Please don't feel picked on. Pilates teachers are trained to pick up on minute, subtle details.

Not sure if this would relate to your fore/aft alignment, but:

Seems like left knee cap is higher than right. Sort of creates a domino effect. Left shoulder is higher, head is slightly to the right. Also, head is slightly foward from the spine and upper back just a little bit hunched. This has some possible causes. If you do many crunches, you are possibly overtraining your torso in flexion, but not enough in extention. Many people who weight train tend to over work their pectorals, while doing insufficient work for rhomboids and lats. This is exacerbated by sitting at a computer for most of the day.
I'll stop at this and let the pros tell you if this would be significant for your skiing.
post #77 of 84

I don't do stomach work - should I? I do a lot of bench presses.

I'm in front of the monitor most of the day. So, what exercises would you recommend I do based on the pictures you've seen?
post #78 of 84
The right knee is in pretty good alignment with the right foot, but the left heel angles out a bit (A closet wedger in the making?????) and the left knee is not as well aligned with its foot. The hips are pushed slightly to the left, thus the dip in the right shoulder and the bend in the neck.

Humans are not symmetrical. We tend to make adjustments that compensate.
post #79 of 84
If you do bench presses, you need to do reverse flys to balance chest to back. Lie on your stomach. Most people need really light weights. ASsk the trainers at the gym to show you this, since it often "loses in the translation". I have also seen postural improvements from people sitting for one hour on a 65cm stability ball.
post #80 of 84
Hey, SCSA, Pierre wanted you to raise the whole front of the foot, leaving just the heels on the floor. Your pic looks like you just raised your toes. It's kind of a measure of your natural ankle flexibility without adding how much it'll stetch when stressed by your weight.
post #81 of 84

Okay, I'll take another picture. My wife will be home in about 2 hours, then I'll post it.
post #82 of 84
SCSA, it does appear that you have a short leg/long leg problem like I had. Hard to tell without an evaluation.
The picture of your ankle flex is incorrect. You must be sitting so your thighs are parallel with the ground. You are sitting to high. Your lower leg is also not 90 degrees to the floor. I can kind of get an idea though. You appear to have about normal range.
post #83 of 84
To me it looks like the boot still has some room to be adjusted to a more upright stance. The pics with you in them seem to suggest the same, but it IS hard to tell without going on the snow. Sounds like HH has you headed in the right direction with them anyway.

MAN I can't wait to ski. It seems like it is so close I can taste it. Kinda like those last few weeks of the fishing season before heading home...but they last soo long..
post #84 of 84
The boots are in their default settings; no forward lean and no canting. I'm not going to do anything else until I ski with HH in November.

Yeah, I know - I'm jonezin big time. For me, it's almost there. Loveland opens Saturday.
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